UNITED NATIONS – The outspoken new U.N. envoy on Syria is briefing the Security Council for the first time after visiting key countries with influence on any possible solution to the deeply entrenched conflict.

Staffan de Mistura is the third such envoy to try to bring the more than three-year civil war to an end. Activists say more than 200,000 people have been killed since protests against the government of President Bashar Assad spiraled into violence in 2011.

De Mistura in recent days has traveled to Iran and Russia to meet with two top allies of Assad.

The U.N.'s deputy humanitarian chief, Kyung-wha Kang, told the council Thursday that big challenges remain in reaching millions in need.